When I bought the X reg, I had the timing belt and thermostat replaced. The Z16SE, like the X16SZR (and as it turns out the C14SE) has the thermostat tucked deep inside the engine, necessitating a big stripdown to replace it.
6 months later, the temperature readings were running at cold while driving, and rising in traffic. Bugger, there it went again. Failed in the open state once more.
Sigh. I’d been watching with interest some discussions on various Vauxhall owners sites about putting a secondary thermostat in the radiator pipework to take over from the awfully located standard unit. Then I saw a chap on EBay selling the “kit” to do it.
I then decided to do it myself. I bought a Renault 4 in-hose thermostat, rated at 89 degrees. Cost of £2. Add to that one hose clamp (have lots spare in the garage), and lets have a play. Loosened the radiator top hose off, and wrestled it off the car. Does the ‘stat fit in the hose? BEAUTIFULLY! Make sure it’s in the right way round, push the hose back onto the engine, clamp the hose to the engine and clamp the ‘stat body firmly in location inside the hose using another clamp.
Refill the cooling system..took it for a run. The gauge went over 100! I was quite alarmed…then all of a sudden it dropped back to 90..then 85ish. Then it sat happily.
Looks like I have have created and then cleared an airlock..heh. Ever since, the car will go to 95/96 degrees initially, then the fans cut in for 30 seconds (at least it gets them moving), and then the stat opens fully and the temp drops down to just under 90. It works most acceptably! If it fails again, it’s a 10 minute job to change it. BETTER.